Antacids FAQ

Annette (Gbemudu) Ogbru, PharmD, MBA

Dr. Gbemudu received her B.S. in Biochemistry from Nova Southeastern University, her PharmD degree from University of Maryland, and MBA degree from University of Baltimore. She completed a one year post-doctoral fellowship with Rutgers University and Bristol Myers Squibb.

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

What are antacids, and how do they work?

Antacids are a class of drugs used to treat conditions caused by the acid
that is produced by the stomach. The stomach naturally secretes an acid called
hydrochloric acid that helps to break down proteins. This acid
causes the contents of the stomach to be acidic in nature, with a pH level of 2 or 3
when acid secretion is active. (pH
levels are a measure of acidity in the stomach: the lower the number, the
greater the acidity.) The stomach, duodenum, and esophagus are protected from
acid by several protective mechanisms. When there is too much acid or protective
mechanisms are inadequate, the lining of the stomach, duodenum or esophagus may
become damaged by the acid, giving rise to inflammation and ulcerations and
their various gastrointestinal
symptoms such as
nausea,
abdominal pain,
and heartburn (due to
gastroesophageal reflux
disease or GERD).

Antacids reduce acidity by neutralizing (counteracting) acid, reducing the
acidity in the stomach, and reducing the amount of acid that is refluxed into
the esophagus or emptied into the duodenum. Antacids also work by inhibiting the
activity of pepsin, a digestive enzyme produced in the stomach that is active
only in an acid environment and, like acid, is believed to be injurious to the
lining of the stomach, duodenum, and esophagus.

It is important to note that when
antacids are taken on an empty stomach they provide acid reduction for 20 to 40
minutes only because the antacid is rapidly emptied into the duodenum. When
taken after a meal, (approximately 1 hour afterwards) antacids reduce acid for
at least three hours since food from the meal slows emptying of the antacid (and
food) from
the stomach. It is important to discuss the use of antacids with a physician or
pharmacist, especially if used in combination with other prescribed medications
so as to avoid drug interactions.